Wireless communication units, such as wireless communications handsets, typically incorporate a number of distinct and operably coupled sub-systems, in order to provide the wide variety of functions and operations that a complex wireless communication unit needs to perform. Such sub-systems may include radiofrequency functions on radiofrequency integrated circuits (RF IC) such as radiofrequency generation, power amplification, (de)modulation, filtering logic, etc. as well as baseband function on baseband integrated circuits (BBIC) such as audio circuits, encoding/decoding, processing logic, etc. and memory units. Typically, a baseband integrated circuit includes one or more baseband modules that can be operably coupled to one or more RF modules on an RF IC. Interfaces are defined for communicating between the respective modules and ICs. For example, the dual-Mode 2.5G/3G BASEBAND/RF IC Interface Standard, from hereon referred to as “DigRF 3G” defines interfaces between the BBIC and the RF IC for dual-mode 3GPP 3G/2.5G (UMTS/EGPRS) implementations.
It is known to provide a wireless communication unit with two or more antennas and two or more receiving paths, e.g. by providing two or more RF modules each connected to a different antenna, in order to improve the performance of the wireless communication unit, which is generally referred to as a receiver spatial diversity scheme.
For example, DigRF defines a physical interconnection between baseband and RF integrated circuits for digital cellular terminals. DigRF 3G defines that the receiver spatial diversity scheme may use two RF ICs, in which case the BBIC has to have a separate contact for each of the RF ICs. United States Patent Application Publication US20070071078 discloses a radio apparatus complying with the Baseband/RF Digital Interface Specification, EGPRS Version, from hereon referred to as “DigRF 2G”. DigRF 2G defines interfaces between the BBIC and the RF IC for 2G/2.5G GSM (E-GPRS) implementations. The radio apparatus disclosed in the aforementioned patent application publication comprises a first radio-frequency unit and a second radio-frequency unit both configured to receive a reception signal transmitted from a communication partner, and configured to transmit a transmission signal to the communication partner. The apparatus further has a baseband processing unit configured to be supplied with the reception signal from each of the first radio-frequency unit and the second radio-frequency unit, and supply, to each of the first radio-frequency unit and the second radio-frequency unit, data to be transmitted to the communication partner, The baseband processing unit is configured to generate a reference signal supplied to each of the first radio-frequency unit and the second radio-frequency unit. A digital signal supplying unit is configured to supply a digital signal containing the reference signal from the baseband processing unit to each of the first radio-frequency unit and the second radio-frequency unit. The baseband processing unit demultiplexes the signal received by each radio-frequency unit, and multiplexes the demultiplexed signals, thereby reconstructing one piece of information.
However, this has the disadvantage that this increases the number of contacts on the BB IC and hence increases costs and size of the BB IC.
The 3G DigRF digital interface standard specifies that, as an alternative, the receiver spatial diversity scheme may be implemented as a single RF IC which has two RF modules connected to a single contact of the RF IC via a multiplexer. However, this increases the costs and the footprint of the RF IC and reduces the flexibility during the manufacturing of the wireless communication unit because it is not possible to select other RF modules than those provided on the RF IC.